Polyester compositions of low residual aldehyde content

ABSTRACT

A mixture of a polyester, such as poly(ethylene terephthalate) PET, and an additive combination, when extrusion compounded exhibits a lower residual acetaldehyde content than does PET alone when similarly treated. The additive combination comprises compounds selected from at least two groups wherein the groups are (i.) poly(vinyl alcohol) or ethylene/vinyl alcohol copolymer, (ii.) polyhydric alcohols and (iii.) polyacrylamide, polymethacrylamide or copolymer of acrylamide or methacrylamide. The invention pertains to any polyester used in the manufacture of bottles or containers which in turn are used to store consumer materials, especially food, beverages and most especially water.

This application claims the benefit under 35 USC 119(e) of U.S.Provisional Application Ser. Nos. 60/259,140, filed Dec. 29, 2000 and60/287,925, filed Apr. 30, 2001.

A mixture of a polyester, such as poly(ethylene terephthalate) PET, andan additive combination, when extrusion compounded exhibits a lowerresidual acetaldehyde content than does PET alone when similarlytreated. The additive combination comprises compounds selected from atleast two groups wherein the groups are (i.) poly(vinyl alcohol) orethylene/vinyl alcohol copolymer, (ii.) polyhydric alcohols and (iii.)polyacrylamide, polymethacrylamide or copolymer of acrylamide ormethacrylamide. The invention pertains to any polyester used in themanufacture of bottles or containers which in turn are used to storeconsumer materials, especially food, beverages and most especiallywater.

BACKGROUND OF THE INVENTION

U.S. Pat. No. 4,361,681 teaches that polyester containing anhydrideend-cap agents have a reduced acetaldehyde generation rate.

U.S. Pat. No. 5,459,224 discloses polyesters having 4-oxybenzylideneend-cap agents to impart improved weatherability and photostability, butno mention is made as to evolution of acetaldehyde. However, it isindicated that such polyesters are suitable for food and beveragepackaging.

Polyesters can be synthesized by a number of routes known in the artusing a variety of catalyst systems. EP 826,713 A1 teaches that lowerlevels of acetaldehyde occur during copolymerization of PET when aphosphite such as bis(2,4-di-tert-butylphenyl)pentaerythritol phosphiteis present during the polymerization.

U.S. Pat. Nos. 4,837,115; 5,258,233; 5,266,413; 5,340,884; 5,648,032 and5,650,469; and WO 93/20147 A1; WO 93/23474 A1; WO 98/07786 and WO98/39388 teach the use of polyamides as a means of reducing theconcentration of acetaldehyde, presumably via a Schiff-base reactionwith the aldehyde, which is reversible in the presence of water.

U.S. Pat. No. 5,856,385 teaches the use of polyamide or amide-wax toreduce the level of acetaldehyde which occurs when sorbitol-basedclarifying agent is heated in polyolefins.

U.S. Pat. No. 5,011,890 describes the suppression of acetaldehydeformation when polyacrylamide, polymethacrylamide or selected acrylamideor methacrylamide copolymers are used in polyacetals. A requirement isthat the polyacrylamide or polymethacrylamide must be “non-meltable” atthe processing temperature of polyacetal. There is no suggestion in thispatent that using polyacrylamide or polymethacrylamide in a polyesterwould reduce the concentration of acetaldehyde in a melt-mixed blendsuch as via extrusion.

Copending application Ser. Nos. 09/603,505 and 09/603,506 disclose theuse of poly(vinyl alcohol) or an ethylene/vinyl alcohol copolymer andpolyhydric alcohols, respectively, towards reducing the residualaldehyde content in PET. Copending application Ser. No. 09/666,679discloses the use of polyacrylamide, polymethacrylamide or an acrylamideor methacrylamide copolymer with at least one ethylenicallyunsubstituted comonomer towards reducing the residual aldehyde contentin PET.

U.S. Pat. No. 4,394,470 discloses a polyethylene terephthalate moldingcomposition with a caramel colorant. The caramel colorant may have beenformed in situ from a mono- or disaccharide.

U.S. Pat. No. 5,681,879 discloses a flame-retardant polyestercomposition comprising a polyester resin, a polyhydric alcohol havingnot less than 3 hydroxyl groups, an inorganic flame retardant and ahalogen-based flame retardant.

WO 00/66659 discloses molding compositions comprising PET and polyhydricalcohol additives for the reduction of acetaldehyde formation.

WO 01/00724 discloses the use of polyols towards reducing acetaldehydeformation in extruded products of PET.

The invention is useful for any polyester where aldehydic compounds,especially acetaldehyde, are formed or evolved during thermal processingof said polyester. Thermal processing of PET includes the synthesis ofPET, thermal exposure during solid state polymerization (SSP), anyinjection molding, injection-blow molding or stretch-blow molding usedin the manufacture of preforms, parissons or bottles and containers, orextrusion of film, or during any melt processing of PET above its glasstransition temperature and below its decomposition temperature.

The instant invention provides for a lower amount of contaminants (e.g.aldehydes) in PET water bottles thus providing for improved taste orflavor in bottled water or other bottled beverages in said PETcontainers. The reduction in the amount of acetaldehyde is highlybeneficial in this respect. Acetaldehyde is known as a decompositionproduct of polyesters such as PET. The acetaldehyde imparts anundesirable taste or flavor to bottled water stored in PET bottles. Ithas been a long sought objective of the industry to reduce the level ofacetaldehyde which migrates out of the PET bottle walls into the wateror other beverage stored therein. A number of engineering or designchanges to extruders, injection molding machines for preforms and bottlemaking machinery have been made to minimize formation of acetaldehydewhen poly(ethylene terephthalate) PET is processed. Modification to thePET composition itself have been made to lower its melting point or itsmelt viscosity in order to allow less severe thermal or mechanicaldamage when PET is processed into preforms or bottles.

The particular additive combination of the present invention provideunexpected benefits in polyester compositions. Certain additivecombinations are synergistic towards prevention of aldehyde formationduring melt processing. Certain other additive combinations unexpectedlyprovide an optimal balance of low color, low haze and high aldehydeinhibition. “Haze” is an undesirable, perceptible graying effect.

DETAILED DISCLOSURE

The instant invention pertains to a polyester composition, stabilizedagainst the formation of aldehydic contaminants during melt processingof said composition, which comprises

(a) a polyester, and

(b) an effective stabilizing amount of an additive combination, whereinthe additives are selected from at least two different groups, whereinthe groups are

(i.) poly(vinyl alcohol) or ethylene/vinyl alcohol copolymer,

(ii.) polyhydric alcohols and

(iii.) polyacrylamide, polymethacrylamide or an acrylamide ormethacrylamide copolymer with at least one ethylenically unsubstitutedcomonomer.

The polyester of component (a) is 95-99.9% by weight of the stabilizedcomposition; and the additive combination of component (b) is 5 to 0.1%by weight of the stabilized composition. Each additive selected from thegroups (i.), (ii.) and (iii.) may be from 1 to 99% by weight of thetotal additive combination of component (b).

The present additive combinations of component (b) may be binarycombinations, for example, a compound from group (i.) and a compoundfrom group (ii.), or a compound from group (ii.) and a compound from(iii.). The additive combinations may, for example, also be ternarycombinations, e.g., a compound from each of the groups (i.), (ii.) and(iii.).

The polyester of component (a) has dicarboxylic acid repeat unitsselected from the group consisting of aromatic dicarboxylic acids having8 to 14 carbon atoms, aliphatic dicarboxylic acids having 4 to 12 carbonatoms, cycloaliphatic dicarboxylic acids having 8 to 12 carbon atoms,and mixtures thereof.

Preferably such diacids are terephthalic acid, isophthalic acid,o-phthalic acid, naphthalene dicarboxylic acid, cyclohexane dicarboxylicacid, cyclohexanediacetic acid, diphenyl-4,4′-dicarboxylic acid,succinic acid, maleic acid, glutaric acid, adipic acid, sebacic acid andmixtures thereof.

Especially preferred are terephthalic acid, isophthalic acid and2,6-naphthalene dicarboxylic acid.

The diol or glycol portion of the polyester of component (a) are derivedfrom the generic formula HO—R—OH where R is an aliphatic, cycloaliphaticor aromatic moiety of 2 to 18 carbon atoms.

Preferably such diols or glycols are ethylene glycol, diethylene glycol,triethylene glycol, propane-1,3-diol, propane-1,2-diol, butane-1,4-diol,pentane-1,5-diol, hexane-1,6-diol, 1,4-cyclohexanedime,3-methylpentane-2,4-diol, 2-methylpentane1,4-diol,2,2-diethyl-propane-1,3-diol, 1,4-di-(hydroxyethoxy)benzene,2,2-bis(4-hydroxycyclohexyl)-propane,2,4-dihydroxy-1,1,3,3-tetramethylcyclobutane,2,2-bis-(3-hydroxyethoxyphenyl)propane,2,2-bis-(4-hydroxypropoxyphenyl)ethane and mixtures thereof.

Most preferably, the diol is ethylene glycol and1,4-cyclohexanedimethanol.

The polyester of component (a) is preferably poly(ethyleneterephthalate) PET or poly(ethylene 2,6-naphthalene-2,6-dicarboxylate);most preferably poly(ethylene terephthalate).

It is also contemplated that the polyester of component (a) can also bea blend of polyesters or copolyesters including components mentionedabove.

It is contemplated that the polyester of component (a) can be virginpolymer or alternatively polymer recyclate. Additionally, it is possibleto combine 80-99% by weight of a polyester with 20-1% by weight of aconcentrate where the concentrate comprises 10-90% by weight of apolyester carrier resin and 90-10% by weight of the additive combinationdescribed for component (b).

The novel polyester compositions provided by this invention are usefulin the manufacture of containers or packages for comestibles such asbeverages and food. Articles molded from these polyesters exhibit goodthin-wall rigidity, excellent clarity and good barrier properties withrespect to moisture and atmospheric gases, particularly carbon dioxideand oxygen.

The plastic containers and films of the present invention are rigid orflexible mono- and/or multi-layered constructions. Typical multi-layerconstructions have two or more layer laminates, manufactured either bythermoforming, or extrusion of multi-layer flexible films, or extrusionof bottle “preforms” or “parissons” followed by subsequent blow moldingof the preforms into bottles. In a multi-layer system, layers of anysuitable plastic may be employed.

Multi-layered containers and films of this invention may for example, beformed from layers of polyesters, polyolefins, polyolefin copolymerssuch as ethylene-vinyl acetate, polystyrene, poly(vinyl chloride),poly(vinylidene chloride), polyamides, cellulosics, polycarbonates,ethylene-vinyl alcohol, poly(vinyl alcohol), styrene-acrylonitrile andionomers, with the proviso that at least one layer comprises a polyestercomposition of the present invention.

For both films and rigid packaging (bottles), typically the exteriorlayer, and innermost layer contacting the contents, are composed ofpolyesters such as PET or PEN [poly(ethylene naphthalate)],polypropylene, or polyethylene such as HDPE. The middle layers, oftencalled ‘barrier’ or ‘adhesive’ or ‘tie’ layers, are composed of one ormore combinations of either PET, PEN, carboxylated polyethylene ionomersuch as Surlyn®, vinyl alcohol homopolymers or copolymers such aspoly(vinyl alcohol), partially hydrolyzed poly(vinyl acetate),poly(ethylene-co-vinyl alcohol) such as EVOH or EVAL, nylons orpolyamides such as Selar® (DuPont) or polyamides based onmetaxylenediamine (sometimes called nylon MXD-6), or polyvinylidenechloride (PVDC), or polyurethanes.

Accordingly, the present invention also pertains to a mono- ormulti-layered plastic container or film, stabilized against theformation of aldehydic contaminants during melt processing of saidcontainer or film, comprising at least one layer which comprises

(a) a polyester, and

(b) an effective stabilizing amount of an additive combination, whereinthe additives are selected from at least two different groups, whereinthe groups are

(i.) poly(vinyl alcohol) or ethylene/vinyl alcohol copolymer,

(ii.) polyhydric alcohols and

(iii.) polyacrylamide, polymethacrylamide or an acrylamide ormethacrylamide copolymer with at least one ethylenically unsubstitutedcomonomer.

Rigid containers may be manufactured by known mechanical processes:

a) Single-stage blow molding such as performed on Nissei, Aoki, orUniloy machines,

b) Two-stage, injection molding of pre-forms such as on Netstal or Huskymachines, and pre-forms converted to bottles by blow molding (e.g., onSidel, Corpoplast and Krones machines),

c) Integrated blow molding of pre-forms to bottles, such as processesconducted on Sipa, Krupp Kautex, or Husky ISB machines, and

d) Stretch blow molding (SBM) of pre-forms to bottles.

The pre-forms may be mono-layer or multi-layer in construction. Thebottles may optionally be post-treated to alter the inner wallproperties. Bottles may optionally be surface treated on the exteriorsuch as by application of surface coatings. UV absorbers and other knownstabilizers may be present in such added surface coatings.

By the use of known heat-setting techniques, certain of the polyestersare, in terms of color, I.V. and heat distortion, stable at temperaturesup to about 100° C. Such stability characteristics are referred toherein as “hot-fill” stability. The linear polyesters most preferred foruse in articles having “hot-fill” stability comprise poly(ethyleneterephthalate), poly(ethylene terephthalate) wherein up to 5 molepercent of the ethylene glycol residues have been replaced with residuesderived from 1,4-cyclohexanedimethanol and poly(ethylene2,6-naphthalenedicarboxylate), wherein the polyesters have beensufficiently heat set and oriented by methods well known in the art togive a desired degree of crystallinity.

The additives of groups (i.), (ii.) and (iii.) are disclosed incopending application Ser. Nos. 09/603,505, 09/603,506 and 09/666,679,the relevant parts of which are each hereby incorporated by reference.

The additive of group (i.) is poly(vinyl alcohol) or an ethylene/vinylalcohol copolymer.

Preferably, the additive of group (i.) is an ethylene/vinyl alcoholcopolymer where the mole ratio of ethylene to vinyl alcohol is 99:1 to1:99. Especially preferred, is the ethylene/vinyl alcohol copolymerwhere the mole ratio of ethylene to vinyl alcohol is 50:50 to 20:80.

The ethylene/vinyl alcohol copolymers of group (i.) can be random orblock copolymers.

The compounds of group (ii.) are polyhydric alcohols of the formula

E—(OH)_(n)

where

n is 2 to 4000, and

E is a hydrocarbyl moiety.

A hydrocarbyl moiety according to this invention is for example analiphatic, cycloaliphatic, aromatic or a mono-, di- or poly-saccharridemoiety.

The hydrocarbyl moieties for the definition of E may be interrupted byheteroatoms, for example by —O—.

Polyhydric alcohols of group (ii.) may be for example glycerin,1,2,3-butanetriol, 1,2,4-butanetriol, erythritol, ribitol, xylitol,dulcitol, sorbitol, 1,2,3-cyclohexatriol, inositol, glucose, galactose,mannose, galacturonic acid, xylose, glucosamine, galactosamine,1,1,2,2-tetramethyloylcyclohexane, 1,1,1-trimethylolpropane,1,1,2-trimethyloylpropane, 1,1,1-trimethylolbutane,1,1,2-trimethylolbutane, 1,1,1-trimethylolpentane,1,1,2-trimethylolpentane, 1,2,2-trimethylolpentane, trimethylolpentane,pentaerythritol, dipentaerythritol, 1,1,3,3-tetrahydroxypropane,1,1,5,5-tetrahydroxypentane, 2,2,6,6-tetrakis(hydroxymethyl)cyclohexaneand 2,2,6,6-tetrakis(hydroxymethyl)cyclohexanol.

The polyhydric alcohol is for instance starch, cellulose or a sugar or asugar alcohol.

The polyhydric alcohols include degraded starch (dextrins andcyclodextrins), maltose and its derivatives, maltitol, maltopentaosehydrate, maltoheptaose, maltotetraose, maltulose monohydrate,D,L-glucose, dextrose, sucrose and D-mannitol.

Commercial polyhydric alcohols include trimethylol propane, triethylolpropane, glycerol, sorbitol and pentaerythritol.

The polymer of group (iii.) is any polymer which contains a polymerizedacrylamide or methacrylamide repeating unit. The preparation ofacrylamide or methacrylamide polymers is generally known.

Preferably, the polymer of group (iii.) is polyacrylamide, or acopolymer of acrylamide with another ethylenically unsaturated monomersuch as methacrylamide, styrene, ethylene, an alkyl acrylate, an alkylmethacrylate, N-vinyl-2-pyrrolidinone or acrylonitrile.

Other preferred comonomers for group (iii.) are the hydroxyalkylmethacrylates, the hydroxyalkyl acrylates or dimethylaminoethylmethacrylate. In these cases, the resulting copolymers contain bothaldehyde reactive amine groups as aldehyde reactive hydroxyl moieties.

Most preferably, the polymer of group (iii.) is polyacrylamide (PERCOL®333, Ciba) or polyacrylamide (PERCOL® 351, Ciba).

The copolymers of group (iii.) can be random or block copolymers.

It is also contemplated that the compositions may contain othercomponents or modifiers such as stabilizers, dispersants, pigments,colorants, UV absorbers, antioxidants, toughening agents, nucleatingagents and fillers as described in U.S. Pat. No. 5,011,890, thepertinent parts of which are incorporated herein by reference.

The instant invention also pertains to a process for preventing theformation of aldehydic contaminants during melt processing of apolyester which comprises

incorporating into said polyester an effective stabilizing amount of anadditive combination, wherein the additives are selected from at leasttwo different groups, wherein the groups are

(i.) poly(vinyl alcohol) or ethylene/vinyl alcohol copolymer,

(ii.) polyhydric alcohols and

(iii.) polyacrylamide, polymethacrylamide or an acrylamide ormethacrylamide copolymer with at least one ethylenically unsubstitutedcomonomer.

The instant invention also pertains to a process for forming a bottlepreform or a PET bottle or container suitable for storing water(mineral, natural, ozonated) or other foodstuffs, which allows thedesirable taste of the water or foodstuff after packaging to remainunaltered after being placed in said bottle or container prepared fromthe polyester composition of the instant invention.

The instant plastic container or film stabilized by a compound orcompounds of component (b) may also optionally have incorporated thereinor applied thereto from about 0.01 to about 10% by weight; preferablyfrom about 0.025 to about 5% by weight, and most preferably from about0.1 to about 3% by weight, based on the total weight of the composition,of additional coadditives such as antioxidants, other UV absorbers,hindered amines, phosphites or phosphonites, benzofuran-2-ones,thiosynergists, polyamide stabilizers, metal stearates, nucleatingagents, fillers, reinforcing agents, lubricants, emulsifiers, dyes,pigments, optical brighteners, flame retardants, antistatic agents,blowing agents and the like, such as the materials listed below, ormixtures thereof.

1. Antioxidants

1.1. Alkylated monophenols, for example2,6-di-tert-butyl-4-methylphenol, 2-tert-butyl-4,6-dimethylphenol,2,6-di-tert-butyl-4-ethylphenol, 2,6-di-tert-butyl-4-n-butylphenol,2,6-di-tert-butyl-4-isobutylphenol, 2,6-dicyclopentyl-4-methylphenol,2-(α-methylcyclohexyl)-4,6-dimethylphenol,2,6-dioctadecyl-4-methylphenol, 2,4,6-tricyclohexylphenol,2,6-di-tert-butyl-4-methoxymethylphenol, nonylphenols which are linearor branched in the side chains, for example,2,6-di-nonyl-4-methylphenol, 2,4-dimethyl-6-(1-methylundec-1-yl)phenol,2,4-dimethyl-6-(1-methylheptadec-1-yl)phenol,2,4-dimethyl-6-(1-methyltridec-1-yl)phenol and mixtures thereof.

1.2. Alkylthiomethylphenols, for example2,4-dioctylthiomethyl-6-tert-butylphenol,2,4-dioctylthiomethyl-6-methylphenol,2,4-dioctylthiomethyl-6-ethylphenol,2,6-di-dodecylthiomethyl-4-nonylphenol.

1.3. Hydroquinones and alkylated hydroquinones, for example2,6-di-tert-butyl-4-methoxyphenol, 2,5-di-tert-butylhydroquinone,2,5-di-tert-amylhydroquinone, 2,6-diphenyl-4-octadecyloxyphenol,2,6-di-tert-butylhydroquinone, 2,5-di-tert-butyl-4-hydroxyanisole,3,5-di-tert-butyl-4-hydroxyanisole, 3,5-di-tert-butyl-4-hydroxyphenylstearate, bis-(3,5-di-tert-butyl-4-hydroxyphenyl) adipate.

1.4. Tocopherols, for example α-tocopherol, β-tocopherol, γ-tocopherol,δ-tocopherol and mixtures thereof (Vitamin E).

1.5. Hydroxylated thiodiphenyl ethers, for example2,2′-thiobis(6-tert-butyl-4-methylphenol), 2,2′-thiobis(4-octylphenol),4,4′-thiobis(6-tert-butyl-3-methylphenol),4,4′-thiobis(6-tert-butyl-2-methylphenol),4,4′-thiobis-(3,6-di-sec-amylphenol),4,4′-bis(2,6-dimethyl-4-hydroxyphenyl)disulfide.

1.6. Alkylidenebisphenols, for example2,2′-methylenebis(6-tert-butyl-4-methylphenol),2,2′-methylenebis(6-tert-butyl-4-ethylphenol),2,2′-methylenebis[4-methyl-6-(α-methylcyclohexyl)phenol],2,2′-methylenebis(4-methyl-6-cyclohexylphenol),2,2′-methylenebis(6-nonyl-4-methylphenol),2,2′-methylenebis(4,6-di-tert-butylphenol),2,2′-ethylidenebis(4,6-di-tert-butylphenol),2,2′-ethylidenebis(6-tert-butyl-4-isobutylphenol),2,2′-methylenebis[6-(α-methylbenzyl)-4-nonylphenol],2,2′-methylenebis[6-(α,α-dimethylbenzyl)-4-nonylphenol],4,4′-methylenebis(2,6-di-tert-butylphenol),4,4′-methylenebis(6-tert-butyl-2-methylphenol),1,1-bis(5-tert-butyl-4-hydroxy-2-methylphenyl)butane,2,6-bis(3-tert-butyl-5-methyl-2-hydroxybenzyl)-4-methylphenol,1,1,3-tris(5-tert-butyl-4-hydroxy-2-methylphenyl)butane,1,1-bis(5-tert-butyl-4-hydroxy-2-methyl-phenyl)-3-n-dodecylmercaptobutane,ethylene glycol bis[3,3-bis(3-tert-butyl-4-hydroxyphenyl)butyrate],bis(3-tert-butyl-4-hydroxy-5-methyl-phenyl)dicyclopentadiene,bis[2-(3′tert-butyl-2-hydroxy-5-methylbenzyl)-6-tetra-butyl-4-methylphenyl]terephthalate,1,1-bis-(3,5-dimethyl-2-hydroxyphenyl)butane,2,2-bis-(3,5-di-tert-butyl-4-hydroxyphenyl)propane,2,2-bis-(5-tert-butyl-4-hydroxy2-methylphenyl)-1,1,5,5-tetra-(5-tert-butyl-4-hydroxy-2-methylphenyl)pentane.

1.7. Benzyl compounds, for example3,5,3′,5′-tetra-tert-butyl-4,4′-dihydroxydibenzyl ether,octadecyl-4-hydroxy-3,5-dimethylbenzylmercaptoacetate,tridecyl-4-hydroxy-3,5-di-tert-butylbenzylmercaptoacetate,tris(3,5-di-tert-butyl4-hydroxybenzyl)amine,1,3,5-tri-(3,5-di-tert-butyl-4-hydroxybenzyl)-2,4,6-trimethylbenzene,di-(3,5-di-tert-butyl-4-hydroxybenzyl) sulfide,3,5-di-tert-butyl-4-hydroxybenzyl-mercapto-acetic acid isooctyl ester,bis-(4-tert-butyl-3-hydroxy-2,6-dimethylbenzyl)dithiol terephthalate,1,3,5-tris-(3,5-di-tert-butyl-4-hydroroxybenzyl)isocyanurate,1,3,5-tris-(4-tert-butyl-3-hydroxy-2,6-dimethylbenzyl) isocyanurate,3,5-di-tert-butyl-4-hydroxybenzyl-phosphoric acid dioctadecyl ester and3,5-di-tert-butyl-4-hydroxybenzyl-phosphoric acid monoethyl ester,calcium-salt.

1.8. Hydroxybenzylated malonates, for exampledioctadecyl-2,2-bis-(3,5-di-tert-butyl-2-hydroxybenzyl)-malonate,di-octadecyl-2-(3-tert-butyl-4-hydroxy-5-methylbenzyl)-malonate,di-dodecylmercaptoethyl-2,2-bis-(3,5-di-tert-butyl-4-hydroxybenzyl)malonate,bis[4-(1,1,3,3-tetramethylbutyl)phenyl]-2,2-bis(3,5-di-tert-butyl-4-hydroxybenzyl)malonate.

1.9. Aromatic hydroxybenzyl compounds, for example1,3,5-tris-(3,5-di-tert-butyl-4-hydroxybenzyl)-2,4,6-trimethylbenzene,1,4-bis(3,5-di-tert-butyl-4-hydroxybenzyl)-2,3,5,6-tetramethylbenzene,2,4,6-tris(3,5-di-tert-butyl-4-hydroxybenzyl)phenol.

1.10. Triazine compounds, for example2,4-bis(octylmercapto)-6-(3,5-di-tert-butyl-4-hydroxyanilino)-1,3,5-triazine,2-octylmercapto-4,6-bis(3,5-di-tert-butyl-4-hydroxyanilino)-1,3,5-triazine,2-octylmercapto-4,6-bis(3,5-di-tert-butyl-4-hydroxyphenoxy)-1,3,5-triazine,2,4,6-tris-(3,5-di-tert-butyl-4-hydroxyphenoxy)-1,2,3-triazine,1,3,5-tris-(3,5-di-tert-butyl-4-hydroxy-benzyl)isocyanurate,1,3,5-tris(4-tert-butyl-3-hydroxy-2,6-dimethylbenzyl)isocyanurate,2,4,6-tris(3,5-di-tert-butyl-4-hydroxy-phenylpropionyl)-hexahydro-1,3,5-triazine,1,3,5-tris(3,5-di-tert-butyl-4-hydroxy-phenylpropionyl)-hexahydro-1,3,5-triazine,1,3,5-tris(3,5-dicyclohexyl-4-hydroxybenzyl)isocyanurate.

1.11. Benzylphosphonates, for exampledimethyl-2,5-di-tert-butyl-4-hydroxybenzylphosphonate,diethyl-3,5-di-tert-butyl-4-hydroxybenzylphosphonate,dioctadecyl3,5-di-tert-butyl-4-hydroxybenzylphosphonate,dioctadecyl-5-tert-butyl-4-hydroxy-3-methylbenzylphosphonate, thecalcium salt of the monoethyl ester of3,5-di-tert-butyl-4-hydroxybenzylphosphonic acid.

1.12. Acylaminophenols, for example 4-hydroxy-lauric acid anilide,4-hydroxy-stearic acid anilide,2,4-bis-octylmercapto-6-(3,5-tert-butyl-4-hydroxyanilino)-s-triazine andoctyl-N-(3,5-di-tert-butyl-4-hydroxyphenyl)-carbamate.

1.13. Esters of β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionic acid withmono- or polyhydric alcohols, e.g. with methanol, ethanol, n-octanol,i-octanol, octadecanol, 1,6-hexanediol, 1,9-nonanediol, ethylene glycol,1,2-propanediol, neopentyl glycol, thiodiethylene glycol, diethyleneglycol, triethylene glycol, pentaerythritol, tris(hydroxyethyl)isocyanurate, N,N′-bis(hydroxyethyl)oxamide, 3-thiaundecanol,3-thiapentadecanol, trimethylhexanediol, trimethylolpropane,4-hydroxymethyl-1-phospha-2,6,7-trioxabicyclo[2,2,2]octane.

1.14. Esters of β-(5-tert-butyl-4-hydroxy-3-methylphenyl)propionic acidwith mono- or polyhydric alcohols, e.g. with methanol, ethanol,n-octanol, i-octanol, octadecanol, 1,6-hexanediol, 1,9-nonanediol,ethylene glycol, 1,2-propanediol, neopentyl glycol, thiodiethyleneglycol, diethylene glycol, triethylene glycol, pentaerythritol,tris(hydroxyethyl) isocyanurate, N,N′-bis-(hydroxyethyl)oxamide,3-thiaundecanol, 3-thiapentadecanol, trimethylhexanediol,trimethylolpropane,4-hydroxymethyl-1-phospha-2,6,7-trioxabicyclo[2,2,2]octane.

1.15. Esters of β-(3,5-dicyclohexyl-4-hydroxyphenyl)propionic acid withmono- or polyhydric alcohols, e.g. with methanol, ethanol, octanol,octadecanol, 1,6-hexanediol, 1,9-nonanediol, ethylene glycol,1,2-propanediol, neopentyl glycol, thiodiethylene glycol, diethyleneglycol, triethylene glycol, pentaerythritol,tris(hydroxyethyl)isocyanurate, N,N′-bis(hydroxyethyl)oxamide,3-thiaundecanol, 3-thiapentadecanol, trimethylhexanediol,trimethylolpropane,4-hydroxymethyl-1-phospha-2,6,7-trioxabicyclo[2,2,2]octane.

1.16. Esters of 3,5-di-tert-butyl-4-hydroxyphenyl acetic acid with mono-or polyhydric alcohols, e.g. with methanol, ethanol, octanol,octadecanol, 1,6-hexanediol, 1,9-nonanediol, ethylene glycol,1,2-propanediol, neopentyl glycol, thiodiethylene glycol, diethyleneglycol, triethylene glycol, pentaerythritol,tris(hydroxyethyl)isocyanurate, N,N′-bis(hydroxyethyl)oxamide,3-thiaundecanol, 3-thiapentadecanol, trimethylhexanediol,trimethylolpropane,4-hydroxymethyl-1-phospha-2,6,7-trioxabicyclo[2,2,2]octane.

1.17. Amides of β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionic acid e.g.N,N′-bis(3,5-di-tert-butyl-4-hydroxyphenylproplonyl)hexamethylenediamide,N,N′-bis(3,5-di-tert-butyl-4-hydroxyphenylpropionyl)trimethylenediamide,N,N′-bis(3,5-di-tert-butyl-4-hydroxyphenylpropionyl)hydrazide,N,N′-bis[2-(3-[3,5-di-tert-butyl-4-hydroxyphenyl]propionyloxy)ethyl]oxamide(Naugard®XL-1 supplied by Uniroyal).

1.18. Ascorbic acid (vitamin C)

1.19. Aminic antioxidants, for exampleN,N′-di-isopropyl-p-phenylenediamine,N,N′-di-sec-butyl-p-phenylenediamine,N,N′-bis(1,4-dimethylpentyl)-p-phenylenediamine,N,N′-bis(1-ethyl-3-methylpentyl)-p-phenylenediamine,N,N′-bis(1-methylheptyl)-p-phenylenediamine,N,N′-dicyclohexyl-p-phenylenediamine, N,N′-diphenyl-p-phenylenediamine,N,N′-bis(2-naphthyl)-p-phenylenediamine,N-isopropyl-N′-phenyl-p-phenylenediamine,N-(1,3-dimethylbutyl)-N′-phenyl-p-phenylenediamine,N-(1-methylheptyl)-N′-phenyl-p-phenylenediamine,N-cyclohexyl-N′-phenyl-p-phenlenediamine,4-(p-toluenesulfamoyl)diphenylamine,N,N′-dimethyl-N,N′-di-sec-butyl-p-phenylenediamine, diphenylamine,N-allyldiphenylamine, 4-isopropoxydiphenylamine,N-phenyl-1-naphthylamine, N-(4-tert-octylphenyl)-1-naphthylamine,N-phenyl-2-naphthylamine, octylated diphenylamine, for examplep,p′-di-tert-octyldiphenylamine, 4-n-butylaminophenol,4-butyrylaminophenol, 4-nonanoylaminophenol, 4-dodecanoylaminophenol,4-octadecanoylaminophenol, bis(4-methoxyphenyl)amine,2,6-di-tert-butyl-4-dimethylaminomethylphenol,2,4′-diaminodiphenylmethane, 4,4′-diaminodiphenylmethane,N,N,N′,N′-tetramethyl-4,4′-diaminodiphenylmethane,1,2-bis[(2-methylphenyl)amino]ethane, 1,2-bis(phenylamino)propane,(o-tolyl)biguanide, bis[4-(1′,3′-dimethylbutyl)phenyl]amine,tert-octylated N-phenyl-1-naphthylamine, a mixture of mono- anddialkylated tert-butyl/tert-octyl-diphenylamines, a mixture of mono- anddialkylated nonyldiphenylamines, a mixture of mono- and dialkylateddodecyidiphenylamines, a mixture of mono- and dialkylatedisopropyl/isohexyidiphenylamines, a mixture of mono- and dialkylatedtert-butyldiphenylamines, 2,3-dihydro-3,3-dimethyl-4H-1,4-benzothiazine,phenothiazine, a mixture of mono- and dialkylatedtert-butyl/tert-octylphenothiazines, a mixture of mono- and dialkylatedtert-octyl-phenothiazines, N-allylphenothiazin,N,N,N′,N′-tetraphenyl-1,4-diaminobut-2-ene,N,N-bis-(2,2,6,6-tetramethyl-piperid-4-yl-hexamethylenediamine,bis(2,2,6,6-tetramethylpiperid-4-yl)-sebacate,2,2,6,6-tetramethylpiperidin-4-one, 2,2,6,6-tetramethylpiperidin-4-ol.

2. UV absorbers and light stabilizers

2.1. 2-(2-Hydroxyphenyl)-2H-benzotriazoles, for example known commercialhydroxyphenyl-2H-benzotriazoles and benzotriazoles as disclosed in, U.S.Pat. Nos. 3,004,896; 3,055,896; 3,072,585; 3,074,910; 3,189,615;3,218,332; 3,230,194; 4,127,586; 4,226,763; 4,275,004; 4,278,589;4,315,848; 4,347,180; 4,383,863; 4,675,352; 4,681,905, 4,853,471;5,268,450; 5,278,314; 5,280,124; 5,319,091; 5,410,071; 5,436,349;5,516,914; 5,554,760; 5,563,242; 5,574,166; 5,607,987 and 5,977,219,such as 2-(2-hydroxy-5-methylphenyl)-2H-benzotriazol,2-(3,5-di-t-butyl-2-hydroxyphenyl)-2H-benzotriazole,2-(2-hydroxy-5-t-butylphenyl)-2H-benzotriazole,2-(2-hydroxy-5-t-octylphenyl)-2H-benzotriazole,5-chloro-2-(3,5-di-t-butyl-2-hydroxyphenyl)-2H-benzotriazole,5-chloro-2-(3-t-butyl-2-hydroxy-5-methylphenyl)-2H-benzotriazole,2-(3-sec-butyl-5-t-butyl-2-hydroxyphenyl)-2H-benzotriazole,2-(2-hydroxy-4-octyloxyphenyl)-2-(3,5-di-t-amyl-2-hydroxyphenyl)-2H-benzotriazole,2-(3,5-bis-α-cumyl-2-hydroxyphenyl)-2H-benzotriazole,2-(3-t-butyl-2-hydroxy-5-(2-(ω-hydroxy-octa-(ethyleneoxy)carbonyl-ethyl)-,phenyl)-2H-benzotriazole,2-(3-dodecyl-2-hydroxy-5-methylphenyl)-2H-benzotriazole,2-(3-t-butyl-2-hydroxy-5-(2-octyloxycarbonyl)ethylphenyl)-2H-benzotriazole,dodecylated 2-(2-hydroxy-5-methylphenyl)-2H-benzotriazole,2-(3-t-butyl-2-hydroxy-5-(2-octyloxycarbonylethyl)phenyl)-5-chloro-2H-benzotriazole,2-(3-tert-butyl-5-(2-(2-ethylhexyloxy)-carbonylethyl)-2-hydroxyphenyl)-5-chloro-2H-benzotriazol,2-(3-t-butyl-2-hydroxy-5-(2-methoxycarbonylethyl)phenyl)-5-chloro-2H-benzotriazole,2-(3-t-butyl-2-hydroxy-5-(2-methoxycarbonylethyl)phenyl)-2H-benzotriazole,2-(3-t-butyl-5-(2-(2-ethylhexyloxy)carbonylethyl)-2-hydroxphenyl)-2H-benzotriazole,2-(3-t-butyl-2-hydroxy-5-(2-isooctyloxycarbonylethyl)phenyl-2H-benzotriazole,2,2′-methylene-bis(4-t-octyl-(6-2H-benzotriazol-2-yl)phenol),2-(2-hydroxy-3-α-cumyl-5-t-octylphenyl)-2H-benzotriazole,2-(2-hydroxy-3-t-octyl-5-α5-fluoro-2-(2-hydroxy-3,5-di-α-cumylphenyl)-2H-benzotriazole,5-chloro-2-(2-hydroxy-3,5-di-α-cumylphenyl)-2H-benzotriazole,5-chloro-2-(2-hydroxy-3-α-cumyl-5-t-octylphenyl)-2H-benzotriazole,-2-(3-t-butyl-2-hydroxy-5-(2-isooctyloxycarbonylethyl)phenyl)-5-chloro-2H-benzotriazole,5-trifluoromethyl-2-(2-hydroxy-3-α-cumyl-5-t-octylphenyl)-2H-benzotriazole,5-trifluoromethyl-2-(2-hydroxy-5-t-octylphenyl)-2H-benzotriazole,5-trifluoromethyl-2-(2-hydroxy-3,5-di-t-octylphenyl)-2H-benzotriazole,methyl3-(5-trifluoromethyl-2H-benzotriazol-2-yl)-5-t-butyl-4-hydroxyhydrocinnamate,5-butylsulfonyl-2-(2-hydroxy-3-α-cumyl-5-t-octylphenyl)-2H-benzotriazole,5-trifluoromethyl-2-(2-hydroxy-3-α-cumyl-5-t-butylphenyl)-2H-benzotriazole,5-trifluoromethyl-2-(2-hydroxy-3,5-di-t-butylphenyl)-2H-benzotriazole,5-trifluoromethyl-2-(2-hydroxy-3,5-di-α-cumylphenyl)-2H-benzotriazole,5-butylsulfonyl-2-(2-hydroxy-3,5-di-t-butylphenyl)-2H-benzotriazole, and5-phenylsulfonyl-2-(2-hydroxy-3,5-di-t-butylphenyl)-2H-benzotriazole.

2.2. 2-Hydroxybenzophenones, for example the 4-hydroxy, 4-methoxy,4-octyloxy, 4-decyloxy, 4-dodecyloxy, 4-benzyloxy, 4,2′,4′-trihydroxyand 2′-hydroxy-4,4′-dimethoxy derivatives.

2.3. Esters of substituted and unsubstituted benzoic acids, as forexample 4-tertbutyl-phenyl salicylate, phenyl salicylate, octylphenylsalicylate, dibenzoyl resorcinol, bis(4-tert-butylbenzoyl) resorcinol,benzoyl resorcinol, 2,4-di-tert-butylphenyl3,5-di-tert-butyl-4-hydroxybenzoate, hexadecyl3,5-di-tert-butyl-4-hydroxybenzoate, octadecyl3,5-di-tert-butyl-4-hydroxybenzoate, 2-methyl-4,6-di-tert-butylphenyl3,5-di-tert-butyl-4-hydroxybenzoate.

2.4. Acrylates and malonates, for example, α-cyano-β,β-diphenylacrylicacid ethyl ester or isooctyl ester, α-carbomethoxy-cinnamic acid methylester, α-cyano-β-methyl-p-methoxy-cinnamic acid methyl ester or butylester, α-carbomethoxy-p-methoxy-cinnamic acid methyl ester,N-(β-carbomethoxy-β-cyanovinyl)-2-methyl-indoline, Sanduvor® PR25,dimethyl p-methoxybenzylidenemalonate (CAS# 7443-25-6), and Sanduvor®PR31, di-(1,2,2,6,6-pentamethylpiperidin-4-yl)p-methoxybenzylidenemalonate (CAS #147783-69-5).

2.5. Nickel compounds, for example nickel complexes of2,2′-thio-bis-[4-(1,1,3,3-tetramethylbutyl)phenol], such as the 1:1 or1:2 complex, with or without additional ligands such as n-butylamine,triethanolamine or N-cyclohexyldiethanolamine, nickeldibutyldithiocarbamate, nickel salts of the monoalkyl esters, e.g. themethyl or ethyl ester, of 4-hydroxy-3,5-di-tert-butylbenzylphosphonicacid, nickel complexes of ketoximes, e.g. of 2-hydroxy-4-methylphenylundecylketoxime, nickel complexes of1-phenyl-4-lauroyl-5-hydroxypyrazole, with or without additionalligands.

2.6. Sterically hindered amine stabilizers, for example4-hydroxy-2,2,6,6-tetramethylpiperidine,1-allyl-4-hydroxy-2,2,6,6-tetramethylpiperidine,1-benzyl-4-hydroxy-2,2,6,6-tetramethylpiperidine,bis(2,2,6,6-tetramethyl-4-piperidyl) sebacate,bis(2,2,6,6-tetramethyl-4-piperidyl) succinate,bis(1,2,2,6,6-pentamethyl-4-piperidyl) sebacate,bis(1-octyloxy-2,2,6,6-tetramethyl-4-piperidyl) sebacate,bis(1,2,2,6,6-pentamethyl-4-piperidyl)n-butyl-3,5-di-tert-butyl-4-hydroxybenzylmalonate, the condensate of1-(2-hydroxyethyl)-2,2,6,6-tetramethyl-4-hydroxypiperidine and succinicacid, linear or cyclic condensates ofN,N′-bis(2,2,6,6-tetramethyl-4-piperidyl)hexamethylenediamine and4-tert-octylamino-2,6-dichloro-1,3,5-triazine,tris(2,2,6,6-tetramethyl-4-piperidyl) nitrilotriacetate,tetrakis(2,2,6,6-tetramethyl-4-piperidyl)-1,2,3,4-butane-tetracaboxylate,1,1′-(1,2-ethanediyl)-bis(3,3,5,5-tetramethylpiperazinone),4-benzoyl-2,2,6,6-tetramethylpiperidine,4-stearyloxy-2,2,6,6-tetramethylpiperidine,bis(1,2,2,6,6-pentamethylpiperidyl)-2-n-butyl-2-(2-hydroxy-3,5-di-tert-butylbenzyl)malonate,3-n-octyl-7,7,9,9-tetramethyl-1,3,8-triazaspiro[4,5]decan-2,4-dione,bis(1-octyloxy-2,2,6,6-tetramethylpiperidyl) sebacate,bis(1-octyloxy-2,2,6,6-tetramethylpiperidyl) succinate, linear or cycliccondensates ofN,N′-bis-(2,2,6,6-tetramethyl-4-piperidyl)-hexamethylenediamine and4-morpholino-2,6-dichloro-1,3,5-triazine, the condensate of2-chloro-4,6-bis(4-n-butylamino-2,2,6,6-tetramethylpiperidyl)-1,3,5-trizineand 1,2-bis(3-aminopropylamino)ethane, the condensate of2-chloro-4,6-di-(4-n-butylamino-1,2,2,6,6-pentamethylpiperidyl)-1,3,5-triazineand 1,2-bis-(3-aminopropylamino)ethane,8-acetyl-3-dodecyl-7,7,9,9-tetramethyl-1,3,8-triazaspiro[4,5]decane-2,4-dione,3-dodecyl-1-(2,2,6,6-tetramethyl-4-piperidyl)pyrrolidin-2,5-dione,3-dodecyl-1-(1,2,2,6,6-pentamethyl-4-piperidyl)pyrrolidine-2,5-dione, amixture of 4-hexadecyloxy- and4-stearyloxy-2,2,6,6-tetramethylpiperidine, a condensation product ofN,N′-bis(2,2,6,6-tetramethyl-4-piperidyl)hexamethylenediamine and4-cyclohexylamino-2,6-dichloro-1,3,5-triazine, a condensation product of1,2-bis(3-aminopropylamino)ethane and 2,4,6-trichloro-1,3,5-triazine aswell as 4-butylamino-2,2,6,6-tetramethylpiperidine (CAS Reg. No.[136504-96-6]); N-(2,2,6,6-tetramethyl-4-piperidyl)-n-dodecylsuccinimid,N-(1,2,2,6,6-pentamethyl-4-piperidyl)-n-dodecylsuccinimid,2-undecyl-7,7,9,9-tetramethyl-1-oxa-3,8-diaza-4-oxo-spiro[4,5]decane, areaction product of7,7,9,9-tetramethyl-2-cycloundecyl-1-oxa-3,8-diaza-4-oxospiro[4,5]decane and epichlorohydrin,1,1-bis(1,2,2,6,6-pentamethyl-4-piperidyloxycarbonyl)-2-(4-methoxyphenyl)ethene,N,N′-bis-formyl-N,N′-bis(2,2,6,6-tetramethyl-4-piperidyl)hexamethylenediamine,diester of 4-methoxy-methylene-malonic acid with1,2,2,6,6-pentamethyl-4-hydroxypiperidine,poly[methylpropyl-3-oxy-4-(2,2,6,6-tetramethyl-4-piperidyl)]siloxane,reaction product of maleic acid anhydride-α-olefin-copolymer with2,2,6,6-tetramethyl-4-aminopiperidine or1,2,2,6,6-pentamethyl-4-aminopiperidine.

The sterically hindered amine may also be one of the compounds describedin GB-A-2301106 as component I-a), I-b), I-c), I-d), I-e), I-f), I-g),I-h), I-i), I-j), I-k) or I-l), in particular the light stabilizer1-a-1, 1-a-2, 1-b-1, 1-c-1, 1-c-2, 1-d-1, 1-d-2, 1-d-3, 1-e-1, 1-f-1,1-g-1, 1-g-2 or 1-k-1 listed on pages 68 to 73 of said GB-A-2301106.

The sterically hindered amine may also be one of the compounds describedin EP 782994, for example compounds as described in claims 10 or 38 orin Examples 1-12 or D-1 to D-5 therein.

2.7. Sterically hindered amines substituted on the N-atom by ahydroxy-substituted alkoxy group, for example compounds such as1-(2-hydroxy-2-methylpropoxy)-4-octadecanoyloxy-2,2,6,6-tetramethylpiperidine,1-(2-hydroxy-2-methylpropoxy)-4-hexadecanoyloxy-2,2,6,6-tetramethylpiperidine,the reaction product of 1-oxyl-4-hydroxy-2,2,6,6-tetramethylpiperidinewith a carbon radical from t-amylalcohol,1-(2-hydroxy-2-methylpropoxy)-4-hydroxy-2,2,6,6-tetramethylpiperidine,1-(2-hydroxy-2-methylpropoxy)-4-oxo-2,2,6,6-tetramethylpiperidine,bis(1-(2-hydroxy-2-methylpropoxy)-2,2,6,6-tetramethylpiperidin-4-yl)sebacate,bis(1-(2-hydroxy-2-methylpropoxy)-2,2,6,6-tetramethylpiperidin-4-yl)adipate,bis(1-(2-hydroxy-2-methylpropoxy)-2,2,6,6-tetramethylpiperidin-4-yl)succinate,bis(1-(2-hydroxy-2-methylpropoxy)-2,2,6,6-tetramethylpiperidin-4-yl)glutarate and2,4-bis{N-[1-(2-hydroxy-2-methylpropoxy)-2,2,6,6-tetramethylpiperidin-4-yl]-N-butylamino}-6-(2-hydroxyethylamino)-s-triazine.

2.8. Oxamides, for example 4,4′-dioctyloxyoxanilide,2,2′-diethoxyoxanilide, 2,2′-dioctyloxy-5,5′-di-tert-butoxanilide,-2,2′-didodecyloxy-5,5′-di-tert-butoxanilide,2-ethoxy-2′-ethyloxanilide, N,N′-bis(3-dimethylaminopropyl)oxamide,2-ethoxy-5-tert-butyl-2′-ethoxanilide and its mixture with2-ethoxy-2′-ethyl-5,4′-di-tert-butoxanilide, mixtures of o- andp-methoxy-disubstituted oxanilides and mixtures of o- andp-ethoxy-disubstituted oxanilides.

2.9. Tris-aryl-o-hydroxyphenyl-s-triazines, for example known commercialtris-aryl-o-hydroxyphenyl-s-triazines and triazines as disclosed in, WO96/28431, EP 434608, EP 941989, GB 2,317,893, U.S. Pat. Nos. 3,843,371;4,619,956; 4,740,542; 5,096,489; 5,106,891; 5,298,067; 5,300,414;5,354,794; 5,461,151; 5,476,937; 5,489,503; 5,543,518; 5,556,973;5,597,854; 5,681,955; 5,726,309; 5,942,626; 5,959,008; 5,998,116 and6,013,704, for example4,6-bis-(2,4-dimethylphenyl)-2-(2-hydroxy-4-octyloxyphenyl)-s-triazine,Cyasorb® 1164, Cytec Corp,4,6-bis-(2,4-dimethylphenyl)-2-(2,4-dihydroxyphenyl)-s-triazine,2,4-bis(2,4-dihydroxyphenyl)-6-(4-chlorophenyl)-s-triazine,2,4-bis[2-hydroxy-4-(2-hydroxyethoxy)phenyl]-6-(2,4-dimetylpenyl)-s-trizine,2,4-bis[2-hydroxy-4-(2-hydroxy-4-(2-hydroxyethoxy)phenyl]-6-(2,4-dimethylphenyl)-s-triazine,2,4-bis[2-hydroxy-4-(2-hydroxyethoxy)phenyl]-6-(4-bromophenyl)-s-triazine,2,4-bis[2-hydroxy-4-(2-acetoxyethoxy)phenyl]-6-(4-chlorophenyl)-s-triazine,2,4-bis(2,4-dihydroxyphenyl)-6-(2,4-dimethylphenyl)-s-triazine,2,4-bis(4-biphenylyl)-6-(2-hydroxyl-4-octyloxycarbonylethylideneoxyphenyl)-s-triazine,2-phenyl-4-[2-hydroxy-4-(3-sec-butyloxy-2-hydroxypropyloxy)phenyl]-6-[2-hydroxy-4-2,4-bis(2,4-dimethylphenyl)-6-[2-hydroxy-4-(3-benzyloxy-2-hydroxypropyloxy)phenyl]-s-triazine,2,4-bis(2-hydroxy-4-n-butyloxyphenyl)-6-(2,4-di-n-butyloxyphenyl)-s-triazine,2,4-bis(2,4-dimethylphenyl)-6-[2-hydroxy-4-(3-nonyloxy*-2-hydroxypropyloxy)-5-α-cumylpheny]-s-triazine(* denotes a mixture of octyloxy, nonyloxy and decyloxy groups),methylenebis-{2,4-bis(2,4-dimethylphenyl)-6-[2-hydroxy-4-(3-butyloxy-2-hydroxypropoxy)-phenyl]-s-triazine},methylene bridged dimer mixture bridged in the 3:5′, 5:5′ and 3:3′positions in a 5:4:1 ratio,2,4,6-tris(2-hydroxy-4-isooctyloxycarbonylisopropylideneoxyphenyl)-s-triazine,2,4-bis(2,4-dimethylphenyl)-6-(2-hydroxy4-hexyloxy-5-α-cumylphenyl)-s-triazine,2-(2,4,6-trimethylphenyl)-4,6-bis[2-hydroxy-4-(3-butyloxy-2-hydroxypropyloxy)phenyl]-ss-triazine,2,4,6-tris[2-hydroxy-4-(3-sec-butyloxy-2-hydroxypropyloxy)phenyl]-s-triazine,mixture of4,6-bis-(2,4-dimethylphenyl)-2-(2-hydroxy-4-(3-dodecyloxy-2-hydroxypropoxy)-phenyl)-s-triazine,and4,6-bis-(2,4-dimethylphenyl)-2-(2-hydroxy-4-(3-tridecyloxy-2-hydroxypropoxy)-phenyl)-s-triazine,Tinuvin® 400, Ciba Specialty Chemicals Corp.,4,6-bis-(2,4-dimethylphenyl)-2-(2-hydroxy-4-(3-(2-ethylexyloxy)-2-hydroxypropoxy)-phenyl)-s-triazineand 4,6-diphenyl-2-(4-hexyloxy-2-hydroxyphenyl)-s-triazine.

3. Metal deactivators, for example N,N′-diphenyloxamide,N-salicylal-N′-salicyloyl hydrazine, N,N′-bis(salicyloyl) hydrazine,N,N′-bis(3,5-di-tert-butyl-4-hydroxyphenylpropionyl) hydrazine,3-salicyloylamino-1,2,4-triazole, bis(benzylidene)oxalyl dihydrazide,oxanilide, isophthaloyl dihydrazide, sebacoyl bisphenylhydrazide,N,N′-diacetyladipoyl dihydrazide, N,N′-bis(salicyloyl)oxalyldihydrazide, N,N′-bis(salicyloyl)thiopropionyl dihydrazide.

4. Phosphites and phosphonites, for example triphenyl phosphite,diphenyl alkyl phosphites, phenyl dialkyl phosphites, tris(nonylphenyl)phosphite, trilauryl phosphite, trioctadecyl phosphite, distearylpentaerythritol diphosphite, tris(2,4-di-tert-butylphenyl) phosphite,diisodecyl pentaerythritol diphosphite, bis(2,4-di-tert-butylphenyl)pentaerythritol diphosphite,bis(2,6-di-tert-butyl-4-methylphenyl)-pentaerythritol diphosphite,diisodecyloxypentaerythritol diphosphite,bis(2,4-di-tert-butyl-6-methylphenyl)pentaerythritol diphosphite,bis(2,4,6-tris(tert-butylphenyl)pentaerythritol diphosphite, tristearylsorbitol triphosphite, tetrakis(2,4-di-tert-butylphenyl)4,4′-biphenylene diphosphonite,6-isooctyloxy-2,4,8,10-tetra-tert-butane,6-fluoro-2,4,8,10-tetra-tert-butyl-12-methyl-dibenzo[d,g][1,3,2]dioxaphosphocin,bis(2,4-di-tert-butyl-6-methylphenyl) methyl phosphite,bis(2,4-di-tert-butyl-6-methylphenyl) ethyl phosphite,2,2′,2″-nitrilo[triethyltris(3,3′,5,5′-tetra-tert-butyl-1,1′-biphenyl-2,2′-dlyl)phosphite],2-ethylhexyl(3,3′,5,5′-tetra-tert-butyl-1,1′-biphenyl-2,2′-diyl)phosphite.

Especially preferred are the following phosphites:

Tris(2,4-di-tert-butylphenyl) phosphite (Irgafos® 168, Ciba SpecialtyChemicals Corp.), tris(nonylphenyl) phosphite,

5. Benzofuranones and indolinones, for example those disclosed in U.S.Pat. Nos. 4,325,863, 4,338,244, 5,175,312, 5,216,052, 5,252,643;DE-A-4316611; DE-A-4316622; DE-A4316876; EP-A-0589839 or EP-A-0591102 or3-[4-(2-acetoxyethoxy)-phenyl]-5,7-di-tert-butyl-3-[4-(2-stearoyloxyethoxy)phenyl]-benzofuran-2-one,3,3′-bis[5,7-di-tert-butyl-3-(4-[2-hydroxyethoxy]phenyl)benzofuran-2-one],5,7-di-tert-butyl-3-(4-ethoxyphenyl)benzofuran-2-one,3-(4-acetoxy-3,5-dimethylphenyl)-5,7-di-t-3-(3,5-dimethyl-4-pivaloyloxyphenyl)-5,7-di-tert-butyl-benzofuran-2-one,3-(3,4-dimethylphenyl)-5,7-di-tert-butyl-benzofuran-2-one, Irganox®HP-136, Ciba Specialty Chemicals Corp., and3-(2,3-dimethylphenyl)-5,7-di-tert-butyl-benzofuran-2-one.

6. Thiosynergists, for example dilauryl thiodipropionate or distearylthiodipropionate.

7. Peroxide scavengers, for example esters of β-thiodipropionic acid,for example the lauryl, stearyl, myristyl or tridecyl esters,mercaptobenzimidazole or the zinc salt of 2-mercaptobenzimidazole, zincdibutyldithiocarbamate, dioctadecyl disulfide, pentaerythritoltetrakis(β-dodecylmercapto)propionate.

8. Polyamide stabilizers, for example copper salts in combination withiodides and/or phosphorus compounds and salts of divalent manganese.

9. Basic co-stabilizers, for example melamine, polyvinylpyrrolidone,dicyandiamide, triallyl cyanurate, urea derivatives, hydrazinederivatives, amines, polyamides, polyurethanes, alkali metal salts andalkaline earth metal salts of higher fatty acids, for example, calciumstearate, zinc stearate, magnesium behenate, magnesium stearate, sodiumricinoleate and potassium palmitate, antimony pyrocatecholate or zincpyrocatecholate.

10. Nucleating agents, for example inorganic substances such as talcum,metal oxides such as titanium dioxide or magnesium oxide, phosphates,carbonates or sulfates of, preferably, alkaline earth metals; organiccompounds such as mono- or polycarboxylic acids and the salts thereof,e.g. 4-tert-butylbenzoic acid, adipic acid, diphenylacetic acid, sodiumsuccinate or sodium benzoate; polymeric compounds such as ioniccopolymers (ionomers).

11. Fillers and reinforcing agents, for example calcium carbonate,silicates, glass fibres, glass bulbs, asbestos, talc, kaolin, mica,barium sulfate, metal oxides and hydroxides, carbon black, graphite,wood flour and flours or fibers of other natural products, syntheticfibers.

12. Dispersing Agents, such as polyethylene oxide waxes or mineral oil.

13. Other additives, for example plasticizers, lubricants, emulsifiers,pigments, dyes, optical brighteners, rheology additives, catalysts,flow-control agents, slip agents, crosslinking agents, crosslinkingboosters, halogen scavengers, smoke inhibitors, flameproofing agents,antistatic agents, clarifiers such as substituted and unsubstitutedbisbenzylidene sorbitols, benzoxazinone UV absorbers such as2,2′-p-phenylene-bis(3,1-benzoxazin-4-one), Cyasorb® 3638 (CAS#18600-59-4), and blowing agents.

The following examples are for illustrative purposes only and are not tobe construed to limit the scope of the instant invention in any mannerwhatsoever.

General—PET bottle grade pellets are subjected to extrusion compoundingto simulate the heat history which PET experiences when thermallyinjection molded into bottle preforms and subsequently stretch-blowmolded into bottles. The efficacy of an additive added to reduce theformation of acetaldehyde is determined by quantitative analysis usingthermal desorption GC-MS after adoption of published methods. Anunstabilized PET is extruded each day to provide a control polymer formeasuring acetaldehyde formation.

Extrusion—PET is pre-dried in vacuo under nitrogen at an oventemperature of about 70° C. to a moisture level of about 30 ppm which isverified on a Mitsubishi VA-O6 moisturemeter. A Leistritz 18 mm or 27 mmcorotating, non-intermeshing twin screw extruder is configured asfollows: set temps=throat (220-230° C.), zones and die (270° C.), actualextrudate melt temperature is 275-280° C., screw at 100-110 rpm, hopperfeeder=10-15 ppm.

PET Pellet Color—Yellowness Index (YI), and L*, a*, b* by ASTM D1925,D65 10 degm specular included, measured on PET pellets using a DCIspectrophotometer.

Acetaldehyde Analysis—The concentration of acetaldehyde in PET isquantitatively determined using a thermal desorption GC-MS methodadapted from B. Nijassen et al., Packaging Technology and Science, 9,175 (1996); S. Yong Lee, SPE ANTEC 1997, pp 857-861; and M. Dong et al.,J. Chromatographic Science, 18, 242 (1980). A general example followsbelow:

The PET samples are analyzed, in duplicate, by weighing 250 mg ofpowdered PET pellets (cryogenically pulverized) in a 5 mL crimp sealedheadspace vial. The sample vial is heated at 120° C. for one hour in aTekmar model 5000 static headspace analyzer. The headspace gas (5 cc) isthen transferred via a heated transfer line to a Fisons MD-800 GC-MSsystem for SIR detection of the acetaldehyde. The acetaldehyde isdetected by monitoring its fragment ions of 29 and 44 m/e. The Total IonCurrent (TIC) of the GC-MS is also monitored in the retention timeregion of 4-8 minutes. By doing this the presence of acetaldehyde in thesamples is confirmed by three different detectors. By using a knownacetaldehyde value for PET, the ratio of peak areas for the known PETresin and for the experimental PET resin blends are compared and theamount of acetaldehyde in the experimental blend can be obtained.

Haze—PET blends are injection molded into 2″×2″×60 mil plaques using aBOY 50M Injection Molder at a die temperature of 550° F. (288° C.). ABYK-Gardner Haze meter is used to measure haze. “Haze” is anundesirable, perceptible graying effect.

EXAMPLE 1

Unstabilized commercial PET (CLEARTUF® 7207, Shell) is used as a controlPET. Several additive combinations listed below demonstrate asignificant reduction in the amount of acetaldehyde (AA) versus theamount seen when unstabilized PET is extrusion compounded. The % AAreduction is the amount less compared to the amount of AA in thecontrol. The total ion current (TIC) data run in triplicate for thecontrol PET has a standard deviation of s=0.35. Parts per million (ppm)additive is based on resin.

Formulation Additives A (control) none B 2500 ppm polyacrylamide,Percol ® 333 (Ciba)  400 ppm poly(vinyl alcohol), PVA C 2500 ppmpolyacrylamide, Percol ® 333 (Ciba) 1600 ppm cellulose D  400 ppmpoly(vinyl alcohol), PVA 1600 ppm cellulose E 2500 ppm polyacrylamide,Percol ® 351 (Ciba)  400 ppm poly(vinyl alcohol), PVA F 2500 ppmpolyacrylamide, Percol ® 333 (Ciba)  400 ppm poly(vinyl alcohol), PVA1600 ppm cellulose G  750 ppm ethylene/vinyl alcohol copolymer, 40%ethylene 2000 ppm starch H  750 ppm ethylene/vinyl alcohol copolymer,40% ethylene 1000 ppm starch 1000 ppm cellulose

The use of the present additive combinations results in the reduction ofacetaldehyde versus the control and provides for excellent color controland low haze formation.

When polyacrylamide, Percol® 333 or Percol® 351 are interchanged in theabove formulations, excellent results for aldehyde inhibition, low colorand low haze are seen. When starch and cellulose are interchanged in theabove formulations, excellent results for aldehyde inhibition, low colorand low haze are seen. When poly(vinyl alcohol), PVA, ethylene/vinylalcohol copolymer, 40%, 38%, 32% or 27% ethylene, are interchanged inthe above formulations, excellent results for aldehyde inhibition, lowcolor and low haze are seen.

What is claimed is:
 1. A polyester composition, stabilized against theformation of aldehydic contaminants during melt processing of saidpolyester, which comprises (a) a polyester, and (b) an effectivestabilizing amount of an additive combination, wherein the additives areselected from two different groups, wherein the groups are (ii.)polyhydric alcohols which are selected from the group consisting ofstarch, cellulose, a sugar or sugar alcohol, trimethylol propane,triethylol propane, glycerol, sorbitol, pentaerythntol ordipentaerythritol, degraded starch (dextrins or cyclodextrins), maltoseor its derivatives, maltitol, maltopentaose hydrate, maltoheptaose,maltotetraose, maltulose monohydrate, D,L-glucose, dextrose, sucrose,and D-mannitol, and (iii.) polyactylamide, polymethacrylamide or anacrylamide or methacrylamide copolymer with at least one ethylenicallyunsubstituted comonomer.
 2. A composition according to claim 1 whereinthe polyester of component (a) is 95-99.9% by weight of the stabilizedcomposition; and the additive combination of component (b) is 5 to 0.1%by weight of the stabilized composition.
 3. A composition according toclaim 1 wherein the polyester of component (a) has dicarboxylic acidrepeat units selected from the group consisting of aromatic dicarboxylicacids having 8 to 14 carbon atoms, aliphatic dicarboxylic acids having 4to 12 carbon atoms, cycloaliphatic dicarboxylic acids having 8 to 12carbon atoms, and mixtures thereof.
 4. A composition according to claim3 wherein the dicarboxylic acid is terephthalic acid, isophthalic acid,o-phthalic acid, naphthalene dicarboxylic acid, cyclohexane dicarboxylicacid, cyclohexanediacetic acid, diphenyl-4,4′-dicarboxylic acid,succinic acid, glutaric acid, adipic acid, sebacic acid and mixturesthereof.
 5. A composition according to claim 4 wherein the dicarboxylicacid is terephthalic acid or 2,6-naphthalene dicarboxylic acid.
 6. Acomposition according to claim 1 wherein the diol portion of thepolyester of component (a) is derived from the generic formula HO—R—OHwhere R is an aliphatic, cycloaliphatic or aromatic moiety of 2 to 18carbon atoms.
 7. A composition according to claim 6 wherein the diol isethylene glycol, diethylene glycol, triethylene glycol,propane-1,3-diol, butane-1,4-diol, pentane-1,5-diol, hexane-1,6-diol,1,4-cyclohexanedimethanol, 3-methylpentane-2,4-diol,2-methylpentane1,4-diol, 2,2-dimethylpropane-1 3-diol,1,4-di-(hydroxyethoxy)benzene, 2,2-bis(4-hydroxycyclohexyl)-propane,2,4-dihydroxy-1,1,3,3-tetramethylcyciobutane,2,2-bis-(3-hydroxyethoxyphenyl)propane,2,2-bis-(4-hydroxypropoxyphenyl)-ethane and mixtures thereof.
 8. Acomposition according to claim 7 wherein the diol is ethylene glycol. 9.A composition according to claim 1 wherein the polyester of component(a) is poly(ethylene terephthalate) PET or poly(ethylene2,6-naphthalene-2,6-dicarboxylate).
 10. A composition according to claim9 wherein the polyester is poly(ethylene terephthalate).
 11. Acomposition according to claim 1 wherein the polyhydric alcohol of group(ii.) is starch, cellulose or a sugar or a sugar alcohol.
 12. Acomposition according to claim 11 wherein the polyhydric alcohol iscellulose or starch.
 13. A composition according to claim 1 wherein thepolyhydric alcohol is selected from the group consisting of degradedstarch (dextrins and cyclodextrins), maltose and its derivatives,maltitol, maltopentaose hydrate, maltoheptaose, maltotetraose, maltulosemonohydrate, D,L-glucose, dextrose, sucrose and D-mannitol.
 14. Acomposition according to claim 1 wherein the polyhydric alcohol isselected from the group consisting of trimethylol propane, triethylolpropane, glycerol, sorbitol, pentaerythritol and dipentaerythritol. 15.A composition according to claim 1 wherein the additive of group (iii.)is polyacrylamide, polymethacrylamide or a copolymer of acrylamide ormethacrylamide with another ethylenically unsaturated monomer which isacrylamide, methacrylamide, styrene, ethylene, an alkyl acrylate, analkyl methacrylate, N-vinyl-2-pyrrolidinone or acrylonitrile.
 16. Acomposition according to claim 15 wherein the additive of group (iii.)is polyacrylamide.
 17. A composition according to claim 1 wherein theadditive of group (iii.) is a copolymer of acrylamide or methacrylamidewith another ethylenically unsaturated monomer which is a hydroxyalkylmethacrylate, a hydroxyalkyl acrylate or dimethylaminoethylmethacrylate.
 18. A process for preventing the formation of aldehydiccontaminants during melt processing of a polyester which comprisesincorporating into said polyester an effective stabilizing amount of anadditive combination, wherein the additives are selected from twodifferent groups, wherein the groups are (ii.) polyhydric alcohols whichare selected from the group consisting of starch, cellulose, a sugar orsugar alcohol, trimethylol propane, triethylol propane, glycerol,sorbitol, pentaerythritol or dipentaerythritol, degraded starch(dextrins or cyclodextrins), maltose or its derivatives, maltitol,maltopentaose hydrate, maltoheptaose, maltotetraose, maltulosemonohydrate, D,L-glucose, dextrose, sucrose, and D-mannitol, and (iii.)polyacrylamide, polymethacrylamide or an acrylamide or methacrylamidecopolymer with at least one ethylenically unsubstituted comonomer.
 19. Amono- or multi-layered plastic container or film, stabilized against theformation of aldehydic contaminants during melt processing of saidcontainer or film, comprising at least one layer which comprises (a) apolyester, and (b) an effective stabilizing amount of an additivecombination, wherein the additives are selected from different groups,wherein the groups are (ii.) polyhydric alcohols which are selected fromthe group consisting of starch, cellulose, a sugar or sugar alcohol,trimethylol propane, triethylol propane, glycerol, sorbitol,pentaerythritol or dipentaerythritol, degraded starch (dextrins orcyclodextrins), maltose or its derivatives, maltitol, maltopentaosehydrate, maltoheptaose, maltotetraose, maltulose monohydrate,D,L-glucose, dextrose, sucrose, and D-mannitol, and (iii.)polyacrylamide, polymethacrylamide or an acrylamide or methacrylamidecopolymer with at least one ethylenically unsubstituted comonomer.
 20. Aplastic container according to claim 19 which is a rigid bottle.